as this would force a decision between the only alternatives male and female. Also, code like

CREATETABLE t (...
sex enum('m','f')NULL,...);

CREATE TABLE t (
...
sex enum('m', 'f') null,
...
);

is now illegal, because leaving it empty is also not an option according to the ruling. There must be a third option.

For many systems the easy way out might be “Do we even need to know”, deleting the existing gender information and stop collecting.

For many others it might be “This is not about Gender, but about your desired mode of address”.

That leads back to a necessary language and grammar update for German, as the language does have three grammatical genders (male, female, neutrum), but it lacking a truly gender neutral mode of address. German “Es” (“it”) is understood to be derogatory or offensive by many, because it conveys a meaning of thing, it objectifies.